Integrated Paleocene calcareous plankton magnetobiochronology and stable isotope stratigraphy: DSDP Site 384 (NW Atlantic Ocean)

At Deep Sea Drilling Site 384 (J-Anomaly Ridge, Grand Banks Continental Ris e, NW Atlantic Ocean) Paleocene nannofossil chalks and oozes (similar to 70 m thick) are unconformably/disconformably underlain (similar to 168 m; upp er Maastrichtian) and overlain (similar to 98.7 m; upper lower Eocene) by s ediments of comparable lithologies. The chalks are more indurated in strati graphically higher levels of the Paleocene reflecting increasing amounts of biosiliceous (radiolarians and diatoms) components. This site serves as an excellent location for an integrated calcareous and siliceous microfossil zonal stratigraphy and stable isotope stratigraphy. We report the results o f a magnetostratigraphic study which, when incorporated with published magn etostratigraphic results, reveals an essentially complete magnetostratigrap hic record spanning the interval from Magnetochron C31n (late Maastrichtian ) to C25n (partim) (late Paleocene, Thanetian). Integrated magnetobiochrono logy and stable isotope stratigraphy support the interpretation of, and con strain the estimated duration of, a short hiatus (similar to 0.9 my) within the younger part of Chron C29r (including the K/P boundary) and an similar to 6 my hiatus separating upper Paleocene (Magnetozone C25n) and upper low er Eocene (Magnetozone C22r) sediments. Some 30 planktonic foraminiferal da tum levels [including the criteria used to denote the Paleocene planktonic foraminiferal (sub)tropical zonal scheme of Berggren and Miller, Micropaleo ntology 34 (4) (1988) 362-380 and Berggren et al., SEPM Spec. Publ. 54 (199 5) 129-212, Geol. Sec. Am. Bull. 107 (11) (1995) 1272-1287], and nearly two dozen calcareous nannoplankton datum levels have been recognized and calib rated to the magnetochronology. Planktonic foraminiferal Subzones P4a and P 4b of (upper Paleocene) Zone P4 are emended/redefined based on the discover y of a longer stratigraphic extension of Acarinina subsphaerica (into at la st Magnetozone C25n). Stable isotope stratigraphies from benthic foraminife ra and fine fraction (<38 mu m) carbonate have been calibrated to the bioch ronology and magnetostratigraphy. A minimum in benthic foraminifer delta(13 )C was reached near the Danian/Selandian boundary (within Chron C26r, plank tonic foraminiferal Zone P3a and calcareous nannoplankton Zone NP4) and is followed by the rise to maximum delta(13)C values in the late Thanetian (ne ar the base of C25n, in Zone P4c and NP9a, respectively) that can be used f or global correlation in the Paleocene. (C) 2000 Elsevier Science B.V. All rights reserved.